Pneumocytis carinii is a opportunistic parasite that causes pneumonia leading to the deaths of many immunocompromised hosts, such as AIDS patients. Current knowledge of the biochemistry, cellular and molecular biology of the organism is limited; the major reason being that there is yet no axenic continuous cultivation methods for this organism. Parasites, however, can be obtained from lungs of infected mammals and separated from contaminating host cells and microbes. Growth of P. carinii with tissue culture cells has been described by several investigators. Up to three serial transfers, each with about a 3-fold increase in cell densities, have been achieved. Recently, limited growth of the organism in axenic culture has been accomplished. This project is aimed at gaining more information concerning the lipids of P. carinii. Pneumocystis lives in a relatively hydrophobic environment that is rich in lung surfactant proteins and phospholipids (mainly dipalmitoyl phosphatidylcholine). There is very little reported on the direct biochemical characterizations of the lipids of Pneumocystis. We plan to systematically characterize these compounds in detail by a variety of biochemical and biophysical procedures. Individual lipid components will be separated and purified by this-layer, column, high performance and gas-liquid chromatographic procedures. The moieties of complex lipids will be released by hydrolysis, separated by chemical and enzymatic procedures and each will be characterized. Definitive characterizations and identifications will be done by high resolution mass spectrometry and fast atom bombardment mass spectrometry. In the event that lipids, significantly different from those synthesized by the host, are identified, these will be considered potential targets for the development of drugs designed for the elimination of the parasite from the host. The lipid composition of P. carinii will be altered by growing the organisms in culture with or without feeder cells in the presence of inhibitors of lipid metabolism or with a variety of lipids and precursor compounds. Cells in culture with and without supplementation will be compared for their relative sensitivities to drugs. These studies, directed at elucidating the lipid composition, are expected to provide insight into the nutrition of P. Carinii. This information should be useful for the eventual formulation of continuous axenic culture media for the organism which in turn would greatly facilitate further biochemical studies as well as drug testing which should eventually lead to the development of better drugs to cure this parasitic infection.